66478734081681 has 8 divisors (see below), whose sum is σ = 90699668204640. Its totient is φ = 43288478006592.

The previous prime is 66478734081673. The next prime is 66478734081703. The reversal of 66478734081681 is 18618043787466.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66478734081681 - 2³ = 66478734081673 is a prime.

It is a super-2 number, since 2×66478734081681² (a number of 28 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (66478734081671) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 257669511816 + ... + 257669512073.

It is an arithmetic number, because the mean of its divisors is an integer number (11337458525580).

Almost surely, 2^{66478734081681} is an apocalyptic number.

It is an amenable number.

66478734081681 is a deficient number, since it is larger than the sum of its proper divisors (24220934122959).

66478734081681 is a wasteful number, since it uses less digits than its factorization.

66478734081681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515339023935.

The product of its (nonzero) digits is 260112384, while the sum is 69.

The spelling of 66478734081681 in words is "sixty-six trillion, four hundred seventy-eight billion, seven hundred thirty-four million, eighty-one thousand, six hundred eighty-one".